If this is true, or will become true soon with a year or two of efficiency improvements and the prices drop another 100x, then why the rush to build lots of new

If this is true, or will become true soon with a year or two of efficiency improvements and the prices drop another 100x, then why the rush to build lots of new datacenters? Is it a bubble? Why won’t we find out that we can get by with the data centers we have after they’ve gone through a machine upgrade cycle?